Construction of quantum well surface from an Nb surface–doped core-shell La-SrTiO3 nanocubes for photocatalytic hydrogen production

Perovskite oxide semiconductors represent as one of the most promising photocatalysts for water splitting for hydrogen production; however, they still suffer from low light harvesting efficiency and low quantum yield. Herein, a nanoscale quantum well core-shell structure is demonstrated as a conceptual novel strategy for the design of high-performance perovskite oxide photocatalyst. A quantum well core-shell structure composed of La-doped SrTiO3 core and Nb-doped SrTiO3 surface is synthesized. Experimental and theoretical simulation demonstrate that the Nb-doped shell with a thickness of ~ 1 nm enables a lower conduction band potential and the formation of quantum confinement effect on the surface, in which the excited electron can be excited from the La-doped SrTiO3 core to the Nb-doped surface and confined on the 2D Nb-doped surface for highly efficient electron-hole pair separation. The quantum well SrTiO3 (QW-SrTiO3) nanocubes exhibit a strong visible light absorption and remarkably prevent the recombination of photogenerated electron-hole pair through the surface quantum confinement effect. Using graphene (GR) as the electron acceptor, the quantum well SrTiO3 nanocubes display the highest photocatalytic H2 production rate of 14.69 mmol h−1 g−1, which is 78 times higher than that of pristine SrTiO3 nanocubes. Furthermore, QW-SrTiO3/GR hybrid also shows excellent stability for hydrogen evolution. The quantum well designed on the SrTiO3 nanoparticles provides an insight for creating novel photocatalysts to tackle environmental and sustainable energy issues.